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[3.14] gh-124694: Document missing ctxkwargs argument in ThreadPoolExecutor (GH-134321) #160460

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ambv merged 1 commit into from
Oct 23, 2026
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[3.14] gh-124694: Document missing ctxkwargs argument in ThreadPoolExecutor (GH-134321) #160460

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28 changes: 24 additions & 4 deletions Doc/library/concurrent.futures.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -119,7 +119,7 @@ Executor Objects
e.submit(shutil.copy, 'src4.txt', 'dest4.txt')

.. versionchanged:: 3.9
Added *cancel_futures*.
Added the *cancel_futures* parameter.


ThreadPoolExecutor
Expand Down Expand Up @@ -161,7 +161,8 @@ And::
# the single worker thread is already waiting for wait_on_future().


.. class:: ThreadPoolExecutor(max_workers=None, thread_name_prefix='', initializer=None, initargs=())
.. class:: ThreadPoolExecutor(max_workers=None, thread_name_prefix='', \
initializer=None, initargs=(), **ctxkwargs)

An :class:`Executor` subclass that uses a pool of at most *max_workers*
threads to execute calls asynchronously.
Expand All @@ -179,6 +180,18 @@ And::
pending jobs will raise a :exc:`~concurrent.futures.thread.BrokenThreadPool`,
as well as any attempt to submit more jobs to the pool.

*ctxkwargs* is a mapping of additional keyword arguments passed to
:meth:`prepare_context`, allowing customization of the worker execution
context.

.. classmethod:: prepare_context(initializer, initargs)

Setting up the necessary context for creating worker instances in a
pool-based executor (for example, in a concurrent environment like
threads or interpreters).

.. versionadded:: 3.14

.. versionchanged:: 3.5
If *max_workers* is ``None`` or
not given, it will default to the number of processors on the machine,
Expand Down Expand Up @@ -208,6 +221,10 @@ And::
Default value of *max_workers* is changed to
``min(32, (os.process_cpu_count() or 1) + 4)``.

.. versionchanged:: 3.14
Added *ctxkwargs* to pass additional arguments to :meth:`prepare_context`
class method.


.. _threadpoolexecutor-example:

Expand Down Expand Up @@ -296,7 +313,8 @@ efficient alternative is to serialize with :mod:`pickle` and then send
the bytes over a shared :mod:`socket <socket>` or
:func:`pipe <os.pipe>`.

.. class:: InterpreterPoolExecutor(max_workers=None, thread_name_prefix='', initializer=None, initargs=())
.. class:: InterpreterPoolExecutor(max_workers=None, thread_name_prefix='', \
initializer=None, initargs=())

A :class:`ThreadPoolExecutor` subclass that executes calls asynchronously
using a pool of at most *max_workers* threads. Each thread runs
Expand Down Expand Up @@ -356,7 +374,9 @@ per :class:`multiprocessing.Process` apply when using :meth:`~Executor.submit`
and :meth:`~Executor.map` on a :class:`ProcessPoolExecutor`. A function defined
in a REPL or a lambda should not be expected to work.

.. class:: ProcessPoolExecutor(max_workers=None, mp_context=None, initializer=None, initargs=(), max_tasks_per_child=None)
.. class:: ProcessPoolExecutor(max_workers=None, mp_context=None, \
initializer=None, initargs=(), \
max_tasks_per_child=None)

An :class:`Executor` subclass that executes calls asynchronously using a pool
of at most *max_workers* processes. If *max_workers* is ``None`` or not
Expand Down
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